3GPP Technical Specification, 3GPP TS 36.211 v10.0, 3rd Generation Partnership Project, Technical Specification Group Radio Access Network, Physical Channels and Modulation (Release 8), France, March 2007, describes physical channels for evolved UTRA, Universal Terrestrial Radio Access.
When specifying a synchronization scheme for a communication system, of course many parameters have to be weighed in order to optimize, in some sense, the performance of the system. That would be true both for the specific synchronization performance, where perhaps improving one design parameter may worsen another and vice versa, but also for the performance of the communication system as a whole due to the chosen synchronization scheme. For instance, for a wireless system there may be constraints on terminals in terms of power consumption, cost of device, radio reception sensitivity and so forth. Such constraints on communication systems and their constituents can be imposed both by standard regulating bodies, as well as by manufacturers themselves wanting to maximize income generating power of their products. Designers of communication systems designing synchronization schemes must bear these problems of design in mind.
A document for agenda item 7.2 of RAN WG1 meeting 48bis titled, Package of PSC and SSC proposals for LTE cell search, R1-071497 Malta, Mar. 26-30, 2007, proposes a package of Primary Synchronization Codes, PSC, and Secondary Synchronization Codes, SSC, design for LTE cell search. The document presents a solution to the problem of how to design PSC synchronization sequences being Zadoff-Chu sequences of length 71, with root indices u=1, 5 and 70.
Another document for agenda item 7.2 of RAN WG1 meeting 48bis titled, Comparison of sequence and structure for P-SCH, R1-071531 Malta, Mar. 26-30, 2007, presents another proposal on how to design synchronization for E-UTRA. In the document, it was proposed to use Zadoff-Chu sequences of length 72, with no specified root indices u.
A further document for agenda item 5.1.3.4 of 3GPP TSG RAN WG1 LTE Ad Hoc titled, Cell-specific signals for initial synchronization and cell identification, R1-060225, Helsinki, Finland, Jan. 23-25, 2006, introduces centrally symmetric signals and a blind reverse differential correlation detection algorithm for detection of the signals without knowledge of their exact waveform. The document also stresses the importance of PAPR (Peak-to-Average-Power-Ratio) values and concludes that all the OFDM synchronization signals, based on different Golay sequences from a set of orthogonal complementary pairs will have small PAPR values, allowing in that way the maximization of the average transmitted power, i.e., the maximization of the received SNR, signal-to-noise ratio, at the cell edge.